Long-term monitoring of weed contamination in flax crops as a basis for developing an effective protection system

The conducted systematic monitoring of weed infestation in flax crops over periods of different anthropogenic loads revealed that during systematic soil cultivation with plows under conditions of extensive farming, 65 species of crop weeds were found in the structure of the weed community with an average number of 125 pcs/m2. The highest density during this period was characterized by Chenopodium album L., Spergula arvensis L., Camelina alyssum (Mill.) Thell. Of the perennials, Elytrigia repens (L.) Nevski and Sonchus arvensis L. were widespread. The level of anthropogenic load increased in the second half of the 30s. XX century led to a decrease in the weediness of flax crops to 86 pcs/m2. At the same time, the development of fallow lands and boundaries contributed to a slight expansion of the species composition of weeds due to the appearance of forest and meadow species on arable land. During this period, the most burdensome weed species were Spergula arvensis L. and Spergularia rubra (L.) J. Presl & C. Presl, Polygonum spp., Amaranthus retroflexus L., Equisetum arvense L., Cirsium setosum (Willd.) Besser , Linaria vulgaris Mill., Taraxacum officinale F.H. Wigg. In modern conditions, along with the soil cultivation factor, the long-term use of herbicides from the 2,4-D group and their derivatives on the crops of dominant grain crops has played a significant role. This contributed to a change in species composition. A total of 73 species were identified in flax crops. On average, there were up to 62 weeds per unit area. The species resistant to 2,4-D had the highest population density: Galium aparine L., Tripleurospermum inodorum (L.) Sch. Bip., Fallopia convolvulus (L.) Á. Löve, Galeopsis spp., from perennial segetal species - glyphosate-resistant Convolvulus arvensis L., Equisetum arvense L. Analysis of the results obtained using nonparametric statistics confirm that the technology of flax cultivation in the 20th century and the first quarter of the 21st century. Has a dominant influence on the species spectrum and the population density of individual weed species.